Electrical connectors for coaxial cable



Jan. 11, 1966 D. KAO

ELECTRICAL CONNECTORS FOR COAXIAL CABLE Filed Dec. 16, 1963 WOW@ WH M myn/fm w m Cm n W uw v m .NHL

United States Patent Oice 3,2292@ Patented dan. ll, l

3,229,2 ELECTRlCAL CNNECTRS FR COAXlAiL CABE Donald Kao, Montebello, Calif., assignor, by mesne assignments, to international Telephone and Telegraph Corporation, New York, NX., a corporation of Maryland Filed Dec. 16, 15363, Ser. No. 331,945 1 Claim. (Cl. 339-177) This invention relates to coaxial electrical connectors and more particularly relates to a new and novel coaxial cable electrical connector construction having special utility for miniature and subminiature connectors, but not necessarily limited to connectors of such small size wherein the electrical connecting members of the connector constitute improved components, and these improved components provide for an improved assemblage of parts which produce a greatly simplified, compact, highly effective connector capable of satisfying the heretofore conilicting electrical and mechanical requirements for such a connector.

Prior to this invention, electrical connectors for coaxial cables have been relatively large in size, and have been considerably complex in their construction as cornpared with the connector of this invention. Also prior known coaxial connectors have been composed of numerous parts with each part requiring a close t and an accurate maintenance of tolerances between the several component parts. In prior connectors of this type it was generally necessary to unite the several component parts by means or threaded screws and sleeve connections mounted over threaded parts. Not only did this construction present a bulky connector which occupied considerably more space than reqiured for the connector of this invention, but also the prior known connectors presented a great deal of diculty in assembling and disassembling as compared with the connector of this invention.

As is well known to those skilled in this art, in many electrical installations it is of paramount importance to obtain a miniaturization of component elements comprising an electrical assembly. The relatively large and bulky connectors known prior to this invention are not suitable for many electrical installations. Also, in addition to the requirement of keeping the connector as small in size as possible, in most installations it is also important to have a simple electrical connector which may be easily and quickly connected and disconnected.

It is, therefore, an important object of this invention to provide an improved electrical connector construction which produces a simplified, compact, highly effective electrical connector.

Another object of this invention is to provide an electrical connector for coaxial cables which assures a hlm mechanical and electrical connection between cables by one operation of slidably inserting a plug into a receptacle and in which such connection is maintained without further adjustment to the connector.

Another object of this invention is to provide an electrical connector wherein an insulation body surrounding a pin contact in one connector member has a conductive coating thereon which is utilized as a contact terminal as well as a shielding element for the connector assembly.

The connector for coaxial electrical cables in accordance with this invention is designed to be used to join coaxial cables having a center conductor surrounded by a dielectric layer and a tubular outer conductor consisting of a layer of metallic braid enclosed in an electrical insulation sheath.

One'part of this connector is a plug which is provided within an electrical insulation body and electrical conducting means covering the outer surface of the insulation body. Means are provided for clampinga portion of metallic braid of the coaxial cable to the electrical conducting means on the outside surface of the insulation body of the plug. Also, within the insulation body are means for establishing a rm mechanical and electrical connection with the center conductor of the coaxial cable.

Attached to the end of the other cable to be joined is a mating socket member. This member includes an electrical conducting body member which includes means for establishing a rm electrical contact with the central body conductor of the coaxial cable and means for clamping a portion of the metallic braid of the cable to the electrical conducting member. Means are provided for melting a firm electrical connection with the outer and central electrical conductors of the mating plug member.

The mating receptacle and plug members are firmly mechanically and electrically connected to each other solely by means of their integral parts which are constructed in such a manner that they can be securely held together by frictional retention.

That these and other objects and advantages are obtained will be readily apparent to those skilled in this art from a consideration of the following detailed description of a preferred embodiment of this invention when reference is made to the accompanying drawings in which:

FIGURE 1 is a sectional view of the connector plug of the electrical connector.

FIGURE 2 is a sectional view of the receptacle of the electrical connector.

FlGURE 3 is a central longitudinal sectional view of a connector plug inserted into the receptacle showing the structural details of the electrical connector establishing a iirm electrical connection between two coaxial cables.

FIGURE 4 is an enlarged sectional view of the shrouded end portion of the connector plug.

FiGURE 5 is a cross-sectional view of the electrical connector of this invention taken along line 5-5 of FIGURE 3.

While the principles of this invention are of general application for coaxial connections, this invention will be described relative to a connector used for interconnecting coaxial cables of the type having a central con ductor surrounded by dielectric which is in turn enclosed by an outer tubular conductor covered by an insulation sheath.

Referring to FIGURE l of the drawings, numeral 10 generally designates one of a pair of complementary connector members. For purposes of identification, connector member 10 is termed a plug member. The other connector member, shown in cross-sectional detail in FIGURE 2, is designated generally by the reference numeral 11 and for purposes of identification is termed a receptacle. The plug member 10 is shown as being secured to the end of a coaxial cable 12 and the receptacle i1 is shown as being secured to the end of a coaxial cable i3. FIGURE 3 of the drawings shows the electrical connector of this invention fully assembled with the plug lil properly positioned within the receptacle 11.

FIGURE 1 shows that plug lll has a tubular body portion 14. The body portion 14 is foi-med from material having good electrical insulation properties for reasons which will become more apparent from the description hereinbelow. The insulation body 14 is provided with a center bore 16 having la rearwardly opening counterbore 17. The center bore 16 and the rearwardly opening counterbore 17 are adapted to receive the center conductor 18 and the dielectric 19 of the coaxial cable l2. The plug 10 also includes a center pin contact member generally designated by the numeral 2l. Although the pin contact member 2l utilized with this connector may take various forms and be of various types, the type of pin ductor 33.

contact shown in FIGURE 1 includes a forward contacting portion 22 and a tubular terminal portion 23. The forward contacting portion 22 is composed of a plurality of twisted Wires. These twisted wires extend rearwardly into the tubular terminal portion 23 and the twisted wires of the forward contact portion are crimped to the tubular terminal portion by a crimp 24 as shown in FIGURE 1.

The rearwardly opening counterbore 17 within the tubular insulation body 14 has a diameter which is approximately equal to the outside diameter of the dielectric 19 lof the coaxial cable 12. As indicated hereinabove the tubular body 14 is formed from a material having good electrical insulation properties tand the body 14 preferably is formed by the precision molding of acetal plastic, a polycarbonate or other suitable plastics or the like. The forward portion 25 of the body 14 has an outside diameter which is substantially less than the outside diameter of the center portion 26 and slightly less than the outside diameter of the rearward or terminal portion 27. The outer surface 28 of the tubular body 14 is prepared in a manner to be more fully described hereinbelow so as to provide an electrical conducting coating 29 over the entire o uter surface of the body 14. The electrical conductive coating 29 on the outer surface 28 off the forward portion 25 of the body 14 constitutes an outer electrical contact for the plug 10. The length of the center pin contact 21 is carefully chosen so that the forward portion 25 of the body 14 extends beyond the length of the pin contact, thus providing the center pin contact, which may be ver-y small in size, protection from damage which could result if the pin contact were jammed, hit or displaced from its installed position Within the plug 10.

In preparing the outer surface 28 of the insulation body 14 for use in the electrical connector of this invention the outer surface, with the exception of the outer surface on the forward and rearward ends 30 `and 31, respectively, is first chemically etched, cleaned and sensitized. Next the outer surface of the body 14 is copper plated by chemical reduction and electrodeposition process. A chemical brightener is added during the electrodeposition process to increase the luster of the copper plating on the surface 28. A final protective plating is then added to give the copper plating protection against corrosion.

The coaxial cable 12 is prepared for insertion into plug by first stripping the sheath 32 from the braided wire conductor 33. The braided wire conductor 33 is then stripped free of the dielectric 19. A portion of the dielectric 19 is stripped free from the center conductor 18. The stripped forward end of the center conductor 18 is then inserted into the tubular terminal portion 23 of the pin contact member 21 from the rear and is secured therein by any suitable means such as by a crimp 34 as shown in FIGURE l. After the center conductor has been crimped to member 21, the remaining portions of the coaxial cable may then be positioned within the plug 10. The center pin contact member 21 is first inserted into the bore 16 until the forward end 35 of the dielectric 19 abuts shoulder 36 of the counterbore 17. With the center conductor and dielectric in this position within plug 10, the rearward portion 27 of the plug 10 is interposed between the dielectric 19 and the braided wire con- A metallic ferrule 66 is then placed over a portion of the insulation sheath and the braided wire conductor and the braided wire conductor is thereby crimped to the outer surface of the plug 10 by means of the metallic ferrule.

FIGURE Z of the drawings shows that the receptacle 11 has a tubular body portion 37. The tubular body 37 is formed from an electrical conducting material for reasons which will become more apparent from the description hereinb'elow. The forward contacting end 38 -of the body 37, as seen to the right in FIGURE 2, contacts the .electrical conductive coating 29 `on the outer surface 2S of the plug 10 when the plug 19 is inserted into the receptacle 11 to form the electrical connector of this invention. The forward contacting end 33 of the conducting body 37 is provided With a plurality of axially directed slits 39 formed therein to divide the forward end 38 into a circumferentially arranged lseries of spring-like tines or lingers 40. The fingers 40 cf the electrical conducting body 37 are bowed toward the center axis of the receptacle 11.

The electrical conducting body 37 of the receptacle has an inside .diameter which is slightly greater than the outside diameter of the dielectric 41 of the coaxial cable 13. The tubular body 37 is provided with a shoulder 42 which is formed on the inner surface 43 of the body 37. A tubular dielectric member 44 having an outside diameter which is approximately equal tothe inside diameter of the body 37 is formed so that the member 44 may be inserted into the tubular body 37 The dielectric member 44 is provided with a shoulder 45 which abuts against the shoulder 42 provided on the inner surface 43 of the body 37. The forward portion 46 of the tubular dielectric member 44 extending forward of the shoulder 45 has an outside diameter wihch is less than the outisde diameter of the rearward portion 47 of the dielectric member. The tubular dielectric member 44 is inserted into the tubular body 37 until the corresponding shoulders 42 and 45 on the body 37 fand the dielectric member 44, respectively, come into abutting relationship.

The coaxial cable 13 is prepared for insertion into the receptacle 11 by first stripping the dielectric 41 free from a portion of the center conductor 48. Next a portion of the braided wire conductor 49 is stripped free from the dielectric 41. Then a portion of the insulation sheath 50 is stripped free from the braided Wire conductor 49. The stripped portion of the center conductor 48 is then inserted into the tubular rear portion 51 of a socket contact member 52. The center conductor 48 is then crimped to the rearward portion off the socket contact member at a point 53, as shown in FIGURE 2. The outside diameter of the socket contact member 52 is approximately equal to the inside diameter of the tubular dielectric member 44 so that the socket member 52 may be contained within the dielectric member 44. After the center conductor 48 has been crimped to the socket member 52, the socket member and the dielectric -of the coaxial cable 13 may then be inserted into the tubular body 37 until the forward edge 54 of the dielectric 41 abuts the rearward edge 55 of the dielectric rmember 44. As the parts of the co- :axial cable which are prepared in a manner as indicated hereinabove are positioned within the electrical conducting body 37, the rearward portion 56 of the body 37 is interposed between the dielectric 41 and the braided wire conductor 49. A metallic ferrule 57 is placed over the braided wire conductor 49and a portion of the insulation sheath 50 and the braided wire conductor is then crimped to the electrical conductive coating 29 on the outer surface 2S of the tubular body 37 by rmeans of the metallic ferrule.

The forward portion 38 of the tubular conducting body 37 is provided with a protective shield 59. The shield 59 may be attached to body member 37 by any well known -attaching methods such as soldering and the like. The end portion 60 of the protective shield 59 is rounded so as to have a configuration which will provide a guide for the plug 10 when the plug is inserted into the receptacle 11. The rounded end portion 60 of the shield 59 guides the plug 10 into contacting relationship with the ybeveled end portions 61 of the receptacle fingers 40. The beveled ends 61 of the fingers 49 further guide the plug 10 into the receptacle 11. As the plug is inserted into the receptacle 11, the resilient force exerted by the fingers 4t) is overcome and the fingers are spread to form an opening having the same diameter as the inserted p0rtion of the plug 10. As the fingers 40 are spread further, they continue to .exert an increased inward force against the electrical conducting coating 29 on the outer surface 28 of 4the plug 10. Thus a positive electrical contact is established between the conductive coating 29 on the outer surface 28 of the plug 10 and the electrical conductive body 37 of the receptacle 11. Since the braided wire conductor 49 of the coaxial cable 13 is iirmly crimped to the rear portion 56 of the conducting body 37, an external shielding circuit is thereby completed between the braided wire conductor 33 of coaxial cable 12 and the braided wire conductor 49 of the coaxial cable 13.

As the plug is inserted into the receptacle 11 past the lingers 40, the -center pin contact 21 of the plug is guided into the socket contact member 52 by the beveled end portions 62 of the socket contact member 52. When the forward portion 22 of the center pin contact 21 has been inserted into the socket contact member 52, the member 52 is interposed between the forward portion 22 of the center pin contact 21 and the insulation body 14 which surrounds the forward portion of the center pin contact. In its fully connected posi-tion within the receptacle 11 the body 14 of the plug 10 contacts the dielectric member 44 within the receptacle and the center pin contact 21 of the plug member contacts socket contact member 52. When the center pin contact 21 of the plug member contacts the socket contact member 52 within the receptacle, an electrical conducting vcircuit is thereby established between the center conductor 18 :of the coaxial cable 12 and the center conductor 48 of the coaxial cable 13. Thus, when the plug 10 is positioned within the receptacle 11 as shown in FIGURE 3 of the drawings, the electrical connector of this invention is completely assembled so as to form a rm mechanical and electrical connection between the two coaxial cables 12 and 13.

While a certain preferred embodiment of 'this invention has been specifically disclosed, it is to be understood that this invention is not to be limited to this particular embodiment as many variations will be readily apparent to those skilled in this art and this invention is to be given its broadest possible interpretation consistent with the prior art.

What I claim is:

An electrical connector having a pair of complementary connector members for interconnecting the ends of two coaxial cables, each yof said coaxial cables having a center conductor, a dielectric surrounding said center conductor and a braided Wire tubular outer conductor surrounding said dielectric, said electrical connector comprising:

a plug member, said plug member including an electrical insulation body,

an electrical conductive coating covering the outer surface of said insulation body,

a ferrule,

said ferrule being adapted to be positioned over the coaxial cable so as to interpose a portion of the metallic braid between said ferrule and the electrical conductive coating covering the outer surface of said insulation body,

Cil

said ferrule clamping the metallic braid to the electrical conductive coating on said insulation body,

an electrical conductive tubular member,

said tubular member being positioned within said insulation body,

one end of said tubular member being mechanically and electrically connected to the center conductor of a coaxial cable, and

a plurality of twisted Wire conductors,

said twisted wire conductors being mechanically and electrically connected to the end of said tubular member opposite the end connected to the center conductor `of the coaxial ca'ble;

a receptacle member, said receptacle member including,

4an electrical conductive body member,

a ferrule,

said ferrule being positioned over the coaxial cable so as to interpose a portion of the metallic braid lbetween said ferrule and said electrical conducting body member,

a portion of said ferrule being superimposed over a portion of the insulation sheath of the coaxial cable,

nger members forming the forward portion of said electrical conductive body member,

said linger members being bowed toward the center axis of said receptacle member,

said linger members having suiiicient resiliency so as to spread open and receive the mating plug member within said receptacle and thereby establish a iirm electrical connection with the electrical conducting outer surface on the mating plug member of said connector,

a tubular electrical conducting member,

said `tubular member having an open bevelled forward end to receive the twisted wire conductors and a rearward end adapted to receive and retain therein the center conductor of a coaxial cable, and

a tubular electrical insulation member,

said tubular electrical insulation member being interposed between the inner surface of said electrical conducting body and the outer surface of said tubular electrical conducting member.

References Cited bythe Examiner UNITED STATES PATENTS 2,163,412 6/1939 Schneider 339-177 X 2,379,942 7/1945 Webber 339-60 2,548,457 4/1951 Wilson 339-177 3,054,981 9/1962 Malek et al. 339-177 3,056,940 i0/ 1962 Winestock 339-177 X 3,091,748 5/1963 Takes et al. 339-177 X FOREIGN PATENTS 900,277 7/ 1962 Great Britain.

JOSEPH D. SEERS, Primary Examiner. W. DONALD MILLER, Examiner. 

